Benthic communities and biodiversity in Thai mangrove swamps

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1. Field studies were conducted at the Klong Kone mangrove swamps in Samut Songkram Province in Thailand. Following a general survey of the mangrove swamps, we selected several points for detailed samplings along two transact lines. These study points were selected in order to cover various environmental conditions in the area : from mud flat to landward fringe of the mangrove forest.2. Temperature and Eh of the sediments and pH,salinity and nutrient concentrations in the interstitial water were measured. Organic matters in the sediments at the mud flat were lower than those inside the forest. We started monitoring works.3. We studied benthic fauna and tree fauna separately, conducting both quantitative and qualitative samplings. In outer mud flat, an alphaeid shrimp, a stomatopod, and ocypodid crabs were regular species encountered. Cockle was also frequent and polychaete worms were regular animals to be sampled. In the seeward ex-mangrove fringe, benthic fauna was similar to that in the mud flat. In the landward fringe of the forest, erobid snails were abundant and neritid gastropod was also found. Two species of ocypodid crabs and sesarmid crabs were prominent members in the mangrove forest fauna. Crabs were collected for analysis of stomach content and allometry studies.4. We had planned to study recolonization process of the discarded mangrove swamps by benthic animals.However, we could not find appropriate places for such study this time.5. For population studies of some useful animals, we selected a cockle (Anadara). After measurement of shell size, cockles were put in the cages and set at several selected plots to follow survival and growth. For the studies of colonization processes of the barnacles, plastic poles were set at several different environments as the settlement substrate for monitoring works.